Techno-Economic Analysis and Life Cycle Assessment of Large Scale Biogas to Methanol Production

Date
2019-07
Authors
Pedro, Godfrey Okeohene
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Publisher
Faculty of Graduate Studies and Research, University of Regina
Abstract

The development of renewable energy products is essential as the world progresses toward sustainability. Renewables are energy collected from sources, which are filled naturally on a human scale. On the other hand, it is impossible to renew non-renewable energy sources only after several hundred million years, leading to many problems, including but not limited to environmental contamination, issues in public health, rising costs and their enduring lifetime. For example, after several hundred million years, when the earth's supplies of fossil fuel get exhausted, it cannot be renewed. This study focused on a techno-economic analysis and life cycle assessment of using a renewable energy source (biogas) to produce methanol. The process design was performed using Aspen HYSYS version 10. Aspen HYSYS is a chemical process simulator used in the mathematically modeling of chemical processes from unit operations to full chemical plants. In doing this, the feed composition of biogas produced from Landfill was used as the material input, and the layout was well detailed and modeled close to industrial application. The results from the plant design indicate that dry reforming using biogas plus partial oxidation can produce methanol with > 99% purity. Parametric sensitivity analysis was performed to determine the appropriate temperature and pressure required for a high conversion of methanol; the parametric sensitivity showed that methanol production is favored at medium temperature and high pressure. Preliminary equipment sizing was done on the heat exchangers in the process to determine the heat-transfer area required; the heat transfer area was defined as 1027m2 and 735.1m2, respectively. The techno-economic analysis revealed that the process is profitable and has an Internal Rate of Return of 20%, Payback Period of 4.76years, Production Cost of US$0.293/kg of produced methanol and Economic Constraint of 0.68. The life-cycle assessment gave a detailed insight on the interaction between the process and the environment and demonstrated that biogas should be cleaned from hydrogen sulphide and ammonia contaminants to prevent the acidification and human toxicity potential caused by those gases. It also suggests the utilization of the inert nitrogen gas purged from the process to prevent the eutrophication potential caused by its presence.

Description
A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Applied Science in Process Systems Engineering, University of Regina. xiv, 99 p.
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